The use of detergency builders as adjuncts to organic water-soluble synthetic detergents and the property which these materials have of improving the overall detergency performance of such detergents are well known phenomena. Polyphosphates have been the most commonly used builders and within this class alkali metal, e.g., sodium and potassium, polyphosphates and pyrophosphates have been most preferred. An important function of builders in detergency is to sequester polyvalent metal ions (e.g., Ca.sup.2+ and Mg.sup.2+) in aqueous solutions of the detergent composition.
In recent years public attention has been drawn to the role of phosphates generally in the life cycle of lakes, and specifically to the contribution by detergent phosphates to this process. An imbalance of nutrients, e.g., carbon, nitrogen, phosphates and the like in lakes appears to adversely affect the ecological balance between algae and fish. The consequence is that an ordinary and natural lake-aging process can be accelerated. Accordingly, there has been considerable effort in recent years directed to the discovery of nonphosphorous materials which would act as effective builders and thus make it possible to formulate highly effective detergent compositions in which phosphorous-containing builders are wholly or partially replaced by nonphosphorous-containing builders.
Because of the human exposure involved in the use of detergent products, it is essential that the ingredients used therein be satisfactory from the standpoint of toxicological safety. Thus, a detergent builder material must be safe, as well as effective.
The compound 2-hydroxyethyl-N,N-diacetic acid (HEIDA) has been disclosed in the literature as an effective nonphosphorous detergency builder. See West German Patent Application DT No. 2314449 to Mooch Domsjo AB, published Mar. 27, 1972, and Environmental Protection Agency Publication EPA-600/2-74-003 by Schwartz et al., pages 36-38, published March 1974. The EPA reference reports that HEIDA is "borderline with regard to both oral and dermal toxicity . . . "
The compound N-(dioxyethylene)-N,N-diacetic acid, also known as N-diethyleneglycol-N,N-diacetic acid, is disclosed, along with HEIDA in Japanese Laid Open Application No. 59/70652, published Apr. 21, 1984. The utility disclosed in this reference is the synthesis of chelating resins in which the iminoacids are appended to a polymeric resinous material such as polystyrene.
The object of the present invention is to provide detergent compositions which contain a safe and effective nonphosphorous detergency builder.